Re: grub fails on a quite regular "search" command, probably due to bios

[Jordan Uggla]

On Fri, Jan 19, 2018 at 1:49 PM, Arbiel (gmx) <address@hidden> wrote:
> Hi everybody
>
> I recently installed several GNU systems (Ubunty family) on a removable
> msdos (4 primary partitions) device. One partition holds a ntfs file
> system and is used as backup of Windows files, a tiny second partition
> (ext2) is used as a shared /grub directory for the systems installed on
> the third lvm partition.
>
> I can boot my own PC (Dell Vostro) from that device, as well as other
> PCs (Samsung, but I don't know the exact model).
>
> I have not been unable to boot a Sony Vaio with this device. The grub
> menu is perfectly displayed. But then grub fails on the "search"
> command, looking for the device address where vmlinuz and initrd.img reside.

Please post your complete grub.cfg.

What happens when it fails? Do you get an error message?

If you're just left at a screen with no new output, how long have you
tried waiting before giving up and powering down the computer?

>
> As the booting is done always from the same device, nothing changes from
> the run on a PC to the run on other one, but the bios. As grub may rely
> on the bios to access the disks, I suppose the issue stems from the bios
> of the Sony Vaio.
>
> In order to bypass the bios, I loaded the nativedisk module and ran a
> first test on my own PC, only to realize that in doing so, I damage the
> lvm partition, and nothing boots any longer.
>
> 1) Is my assumption concerning the source of the issue correct ? If not,
> what other assumptions can be done ?

It's likely a combination of a problem with your BIOS and a problem
with some drive connected to your computer. When that drive (which
could even be something like an empty SD card reader) is probed, it
causes your BIOS to block and either freeze indefinitely or just wait
for a very long timeout before returning an error message / results to
grub.

> 2) Can really nativedisk have hurt my lvm partition ?

Grub never writes to disks when native drivers are enabled (and only
writes to disk in very specific limited conditions even when not using
native drivers, one of those conditions being never writing to LVM
volumes) so I doubt very much that grub itself caused any problem with
LVM. Trying to boot a distribution with the wrong kernel parameters /
initramfs could potentially have caused problems with LVM (though I
can't think of a specific way that could happen off hand).

> 3) is nativedisk a theorical solution to the issue, and should it be
> used only in case the "regular" boot fails ?

nativedisk is a theoretical solution to this issue, assuming the issue
is what I described above, but there are also other ways that the
problem might be worked around. For example, since we know that the
partition we need to search for is on the same drive as our initial
$root we can avoid probing any other drives when looking for it
(though that will require manually editing the grub.cfg and either not
using the search command at all or only using search with --hint ).

> 4) Is it possible to have grub accessing the various vmlinuz and
> initrd.img files from the ntfs partition where there is plenty of room
> to copy them (the ext2 partition is not large enough) ; I tried but
> received a "file is not available" error message.

Grub can read from ntfs without issue. If you'd like to try this route
please explain more about how you tried to access the files from grub.

-- 
Jordan Uggla (Jordan_U on irc.freenode.net)